Polymeric viologens as electron donors in hydrogen production by intact cells of Clostridium pasteurianum, Desulfovibrio desulfuricans, and Rhodospirillum rubrum

The behaviour of 5 polymeric viologens 2a – e as electron donors in the production of hydrogen by intact cells of Cl. pasteurianum, D. desulfuricans, and R. rubrum was studied. The hydrogen production was followed by gas chromatography and the results indicate that Cl. pasteurianum and D. desulfuricans are much more active than R. rubrum. Polymeric viologens 2a – e show lower initial rates than the low molecular weight viologens 1a and 1b. However, this is independent of the final amount of hydrogen produced, since the polymers are as efficient or more efficient than 1a and 1b. The results are briefly discussed in terms of redox potentials, substituent effects and conformational factors.